Since the development of Metoclopramide (The Merck Index, 11th Edition, 6063) as an antiemetic agent and a gastrointestinal prokinetic agent, various substituted benzamide derivatives having antiemetic activity and gastrointestinal stimulating activity have been provided.
For example, The Merck Index (11th edition, 2344) discloses Clebopride which is a benzamide derivative having a piperidine ring and is useful as antiulcer agent. The Merck Index (11th edition, 2318) discloses Cisapride useful as a gastrointestinal prokinetic agent. These drugs are widely used clinically. In addition, Japanese Patent Unexamined Publication No. (Sho)55-92384 discloses that benzamide derivatives substituted with an azabicyclo ring have antiemetic activity and gastrointestinal stimulating activity and that they are useful as an antiemetic agent and a gastrointestinal prokinetic agent.
However, these substituted benzamide derivatives are not sufficiently useful since they do not have stimulating activity on lower digestive tracts such as the large intestine, although they have stimulating activity on upper digestive tracts such as the stomach. Furthermore, these substituted benzamide derivatives are not satisfactory from a safe standpoint since they sometimes cause adverse reactions such as extrapyramidal syndrome or hyperprolactinemia.
Accordingly, an object of the present invention is to provide medicament for the treatment of gastrointestinal diseases having stimulating activity not only on upper digestive tract but on lower digestive tract and reduced side effects.
The inventors of the present invention conducted various studies to achieve the aforementioned object, and found that novel benzamide derivatives of the present invention have stimulating activity both on upper digestive tract and lower digestive tract. The inventors also found that these novel benzamide derivatives have reduced side effects and are useful as medicament for the treatment of gastrointestinal diseases having excellent selectivity. The present invention was achieved on the basis of these findings.